Meet the team: The Levitators
Near-Field Acoustic Levitation (NFAL) is a phenomenon that occurs when a vibrating plate causes an object above or below it to levitate under the pressure field created by the vibrations. This effect has uses in many fields: in low-friction bearings, non-contact micro-assembly, the production of ultrasonic motors and the transport of delicate objects. Therefore, it is essential to understand the behaviour of acoustically-levitated objects under different conditions to be able to develop this technology. With no standard, universally-applicable theory describing the behaviour of objects in NFAL, hypergravity can be used as a useful tool to judge the validity of the current models. NFAL is often modelled as a standing-wave with the wave reflecting off the levitating object or by a film of high-pressure gas, creating a repulsive force on the object. However, not all behaviour of levitated objects is in agreement with the models when experiments are conducted; for example, the object is attracted towards the plate at certain distances and frequencies. So far, no investigations into NFAL have been performed in high- or microgravity conditions, and we believe the behaviour of the object could be elucidated by accentuating the factors that are increased with high gravity.
To this end, as three Durham University (United Kingdom) undergraduate Physics students, we aim to investigate the exact behaviour of NFAL in hypergravity and therewith further our understanding of this phenomenon. Any insights this investigation may provide into the models which best describe the data could have implications on the extent to which NFAL can be used. Should we find that the effects of gravity cause deterioration or improvement of the effect, this knowledge would have implications on the applicability of NFAL to accelerating systems or even high-gravity environments that might be found, for example, during space travel.
To accomplish these tasks, we will measure the levitation height, resonance frequency & amplitude and the net force acting on the levitated object. Such measurements will be done for varying gravity intensities and transducer frequencies and amplitudes. We aim to use laser-based distance meters and sensitive scales to measure the position of, and the force on, the object as a function of time.